The function of a pipe-chamber feeder consists of the periodical alternate filling of the chambers with slurry at low pressure, and emptying them at high pressure. While performing this function, the closing appliances, especially valves or sliding valves must be opened and closed by a suitable actuating device in a certain sequence and at short time periods, most advantageously in a manner as it is described in the Hungarian Patent Specification No. 160 526. However, the closing elements of the valves have to be moved slowly because a quick closing would cause disadvantageous pressure and velocity fluctuations, even heavy water impacts that are called water hammer in the art concerned.
Consequently, in prior art devices the change-over or switch-over steps i.e. the closing and opening of the valves are relatively slow and they result in a disadvantageous decrease of the performance of transport equipments having only two pipe chambers. In such equipments every change-over consists at least of two opening and closing steps, and during the change-over operations filling or emptying of the pipe chambers is not possible.
If three or more pipe-chambers are used there is no such decrease of the output. However, investment and operating costs of equipments having three or more pipe-chambers are much too high. In addition to this, a diminishing of the time necessary for the switch-over steps is still desirable even if the number of pipe-chambers is more than two.
The fact that the change-over steps in the known prior art hydraulic transport equipments are extremely time-consuming is specially disadvantageous with large-size equipments because the speed of actuation of the closing elements of big closing appliances is very slow, and also the pressure-changes in the large pipe-chambers take much time.